System and methods for network slice reselection

ABSTRACT

There is provided method for managing network resources by switching the slice used to support a user equipment (UE), in a process referred to as slice handover or slice switching. There are several reasons why a slice handover may be implemented, include movement of the UE and network load balancing. Further the UE can be switched to a new slice operated by the same service provider (intra-operator handover) or a different service provider (inter-operator handover).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/662,651, entitled “SYSTEM AND METHODS FOR NETWORK SLICE RESELECTION”filed Oct. 24, 2019, which is a continuation of U.S. patent applicationSer. No. 15/233,285, filed Aug. 10, 2016 entitled “SYSTEM AND METHODSFOR NETWORK SLICE RESELECTION” and claims the benefit of priority toU.S. Patent Application Ser. No. 62/220,731, entitled “SYSTEM ANDMETHODS FOR NETWORK SLICE HANDOVER” filed Sep. 18, 2015 which are herebyincorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention pertains to the field of communications networks,and in particular to systems which implement network slicing.

BACKGROUND

Communication networks enabled by technologies such as Network FunctionVirtualization and Software Defined Networking, may be flexiblyorganized so as to serve various customer demands. In building advancednetworks, such as those to support future developments in wirelessnetworks (including next generation, or so-called Fifth Generation (5G)wireless networks), network slicing provides the ability to createisolated virtual networks over which different traffic flows can travelisolated from each other. However, managing variable and competingdemands on a potentially large network scale is a complex propositionrequiring an effective architecture and management thereof.

Network operators serve different sets of demand for different types ofUEs using different services. As the number of supported servicesincreases, the differences in the traffic profiles associated with thedifferent services is likely to become more stark. To support aplurality of different services each of the services associated withdifferent types of UEs, the network will need to support thetransmission and mobility profiles of all the devices. Typically thishas meant that the network is designed with the assumption that each UEhas to be assigned sufficient resources to accommodate the most extremetransmission and mobility profiles. As the number of devices andservices increase, this may pose a large burden on the network operatorand may result in heavily over-provisioned networks When a userequipment (UE) associated with an existing slice, moves to anotherlocation, there is no guarantee that the UE can attach to the existingslice in the new location. Accordingly, there is a need for a system andmethod that at least partially addresses one or more limitations of theprior art.

This background information is provided to reveal information believedby the applicant to be of possible relevance to the present invention.No admission is necessarily intended, nor should be construed, that anyof the preceding information constitutes prior art against the presentinvention.

SUMMARY

An object of embodiments of the present invention is to provide a systemand methods for network slice reselection/handover. In accordance withembodiments of the present invention, there is provided a method formanaging network resources by switching the slice used to support a userequipment (UE), in a process referred to as slice handover or slicereselection. There can be several triggers for a slicehandover/reselection including: movement of the UE, changes to themobility requirements of the UE, a slice management event, and in someembodiments network load balancing. A slice management event includesthe instantiation of a slice, the termination of a slice or themodification of the capacity a slice. Further the UE can be switched toa new slice operated by the same service provider (intra-operatorhandover) or a different service provider (inter-operator handover).

In accordance with an aspect of the present invention, there is provideda method for network slice reselection. Such a method includesreceiving, over a network interface, an indication that a slicereselection triggering event associated with a mobile device attached toa first slice has occurred. Such a method can further include selectinga second slice as a target slice, and initiating a migration of themobile device to the selected target slice. In some embodiments thefirst slice and the second slice are operated by the same serviceprovider. In some embodiments the first slice and the second slice areoperated by different service providers. In some embodiments thereceived indication that a slice reselection triggering event hasoccurred is indicative of a change in the service requirements of themobile device. In some embodiments the received indication is indicativeof the mobile device receiving a clearer signal from a second accesspoint. In some embodiments the received indication is indicative ofchanges to the mobility requirements of the mobile device. In someembodiments the received indication is indicative of the occurrence of aslice management event. In some embodiments a slice management event isselected from the group consisting of: creating a new slice; terminatingan existing slice; and modifying the capacity of an existing slice. Insome embodiments initiating the migration of a mobile device to thetarget slice further includes initiating the migration of a group ofmobile devices to the target slice. In some embodiments initiating amigration of the mobile device to the selected target slice includessending messages to network components in order to migrate the mobiledevice to the target slice. In some embodiments the method is executedby a node implementing a network slice selection function and the firstslice belongs to a first network. In such embodiments, responsive toslice selection function determining that the mobile device can bemigrated to a second slice within the first network, selecting thesecond slice and transmitting an instruction towards the mobile deviceto instruct the mobile device to connect to the second slice. In someembodiments, the method can further include selecting a slice in asecond network, and wherein initiating the migration further includestransmitting a request for admission of the mobile device to a slicetowards a node in the second network. In some embodiments the receivedindication that a slice reselection triggering event has occurred isindicative of a change in the service requirements of the mobile device,and is further indicative of a movement of the mobile device to aservice area associated with the second network. In some embodiments theslice reselection event occurs when differing capacities between networkslices reaches a load-balancing threshold; in which case receiving atrigger for a slice reselection based on the occurrence of a slicereselection event includes receiving a trigger from a load monitoringfunction which measures the capacities loads of the slices.

Another aspect of the present invention slice selection function. Such aslice selection function includes a network interface for receivingindications of triggering events and for transmitting instructions, aprocessor and a non-transient memory for storing instructions. Theinstructions, when executed by the processor, cause the slice selectionfunction to, upon receiving an indication that a slice reselectiontriggering event associated with a mobile device attached to a firstslice has occurred, select a second slice as a target slice; and toinitiate a migration of the mobile device to the selected target slice.In some embodiments a slice reselection triggering event occurs whenthere is a change in the service requirements of the mobile device. Insome embodiments the service requirements of the mobile device changesin response to changes to the mobility requirements of the mobiledevice. In some embodiments the service requirements of the mobiledevice changes in response to the movement of the mobile device. In someembodiments the instructions which cause the slice selection function toinitiate a migration of the mobile device to the selected target sliceincludes instructions which cause the slice selection function to sendmessages to network components in order to migrate the mobile device tothe target slice. In some embodiments the slice reselection triggeringevent includes a slice management event selected from the groupconsisting of: creating a new slice, terminating an existing slice, ormodifying the capacity of an existing slice.

BRIEF DESCRIPTION OF THE FIGURES

Further features and advantages of the present invention will becomeapparent from the following detailed description, taken in combinationwith the appended drawings, in which:

FIG. 1 illustrates an overview of the communication network architecturein accordance with embodiments of the present invention.

FIG. 2 illustrates an overview of another communication networkarchitecture in accordance with embodiments of the present invention.

FIG. 3 illustrates an overview of another communication networkarchitecture in accordance with embodiments of the present invention.

FIG. 4 illustrates a system for virtual infrastructure managementincluding first and second Operators having internal InfrastructureManagement functions in accordance with embodiments of the presentinvention.

FIG. 5 illustrates a procedure for intra-operator slice handover inaccordance with embodiments of the present invention.

FIG. 6 illustrates a procedure for inter-operator handover according toa first option in accordance with embodiments of the present invention.

FIG. 7 illustrates a procedure for inter-operator handover according toa second option in accordance with embodiments of the present invention.

FIG. 8 illustrates a procedure for slice reselection for load balancingaccording to embodiments of the present invention.

FIG. 9 is a flowchart illustrating a procedure for slice reselectionaccording to embodiments of the present invention.

FIG. 10 is a block diagram of a processing system which can host thevarious functions described herein, according to an embodiment.

It will be noted that throughout the appended drawings, like featuresare identified by like reference numerals.

DETAILED DESCRIPTION

As used herein, a “network” or “communication network” may serve variousdevices including but not necessarily limited to wireless devices. Sucha network may include a radio access portion and backhaul portion. Thenetwork may further comprise various virtualized components as willbecome readily apparent herein. A primary example of such a network is5G network which is reconfigurable and capable of network slicing, asdescribed below.

Network slicing is a network management technique in which both computeand connectivity resources in a communications network are divided tocreate a set of isolated virtual networks. When combined with othertechniques such as Network Function Virtualization (NFV), VirtualNetwork Functions (VNFs) can be instantiated upon generic computingresources to provide specific network functions. This allows differentslices of the compute and connectivity resources to be put together intoa set of network slices, each of which is isolated from the otherslices. The connectivity between these computing resources can beallocated so that traffic associated with each network operator isisolated from another. Isolation of the resource usage and trafficwithin a slice allows for different services to be isolated on differentslices. Through the use of NFV, the capability and location of thenetwork functions can be adjusted to suit the specific needs of eachoperator within their allocated slice. A first network slice may beconfigured to suit the needs of a Machine Type Communication (MTC)service that generates large number of short transmissions, where MTCdevices do not need ultra-reliable connections because reliability canbe designed at the application layer. This network slice would differ inits configuration and resource demands from a network slice that isdesigned to serve the needs of User Equipment connecting for thepurposes of an enhanced-Mobile-Broadband (eMBB) connection. By providingdifferent slices for different services, an operator can ensure that thespecific needs of a service are met without requiring theoverprovisioning of resources to each connection that would be requiredif a single slice was used for all services. It will be understood thatthe slices created to serve the needs of different services may be builtupon the resources allocated to the network operator within a slice thatisolate the network operator from other network operators on a set ofresources associated with a service provider. It is anticipated thatnetwork slicing techniques, as well as Network Function Virtualizationtechniques will be employed in future generations of mobile networks,including so-called fifth generation (5G) communications networks thatare used to provide network services to mobile devices such as UEs.

In some embodiments a method for managing network resources includesreceiving a trigger indicating a service to a user equipment (UE) shouldswitch from a first network slice to another network slice.

As noted above, a carrier typically operates a network as a collectionof computing and connectivity resources. To ensure that services withdramatically different network usage profiles are accommodated withoutmassively over-provisioning the networks, the underlying networkresources can be used as a base upon which network slices areinstantiated. Each network slice can operate as a virtualized privatenetwork dedicated to a service or a type of traffic. Traffic can becontained within the slice so that there is a degree of trafficisolation between two slices. The parameters of each slice can bematched to a service, so that, for example, a slice used formachine-type communication (MTC) devices that is used for reportingusage and status information from a set of connected utility meters willbe differently selected than the parameters of a slice that is used formobile broadband (MBB) communications. In the above example, an MTCslice may be designed to support a large number of connected devicesthat each transmit small delay-insensitive messages, while the MBB slicemay be designed for a smaller number of connected devices, butprovisioned to provide each of the devices with higher data rate and lowlatency connections. Through the use of Network Function Virtualization(NFV) computing resources can be used to create a configurable set ofnetwork functions within a slice, where needed. This can provide theslice a logical topology specific to its needs. A network slice (asdefined in 3GPP TR 22.891 entitled “Study on New Services and MarketsTechnology Enablers” not yet released) is a collection of logicalnetwork functions that supports the communication service requirementsof a particular network service. One use of network slicing is in thecore network. Through the use of network slicing, different corenetworks can be run on the same or overlapping physical set of networkand computing resources. Network slicing can also be used to createindependent virtual networks dedicated to particular types of networktraffic. It should be understood that this discussion is not intended toexclude the application of network slicing as it applies to the radioaccess edge of the Radio Access Network (RAN), which may need specificfunctionality to support multiple network slices or partitioning ofresources for different network slices. In order to provide performanceguarantees, the network slices can be isolated from each other so thatone slice does not negatively affect the other slices. The isolation isnot restricted to different types of services, but also allows theoperator to deploy multiple instances of the same network partition.

In a conventional mobile network, a UE is associated with a MobilityManagement Entity (MME) during the attach process. The MME associatedwith the mobile device is selected from a pool of MMES by a selectionfunction in a network infrastructure component such as the eNodeB. Incontrast with a single network that must be designed to meet the needsof each wireless device, network slicing allows the instantiation of aplurality network slices on the physical network resources. Each of theslices can be created so that it has characteristics tailored to theparticular requirements of a single network service. The use of networkslices allows for the isolation of different types of traffic, whicheach may have different packet processing requirements and QoSrequirements. Network slicing may correspond to the allocation of pooledresources to offer different services to different customers or groupsof customers. Accordingly, different services can be supported bydifferent customized virtual networks, where the different customizedvirtual networks are substantially separate from one another from thecustomer's point of view. The pooled resources may be commercialhardware components that are configured to provide differentfunctionality through the use of function virtualization, such as NFV.By virtualizing the functions needed at the locations that they arerequired, when they are required, the slice can be provided the networkfunctions to handle the designated traffic and processing requirements.

The Network Function Virtualization (NFV) framework can be used todefine a plurality of virtual network functions (VNFs), each of whichcan correspond to a function enabling operation of a communicationnetwork. For example a VNF can provide the functions of a router,switch, gateway, firewall, load balancer, server and the like. Asopposed to conventional deployments in which dedicated physical nodesare deployed to carry out specified functions, a virtual function can beinstantiated on demand using available computing and connectivityresources. As demand for the function increases, the resources allocatedto the function can be increased. If demand for the function ceases, thefunction can be terminated. As such, VNFs may be instantiated on anas-needed basis using available resources. NFV and virtual networkfunctions architecture is described in ETSI GS NFV 001 entitled “NetworkFunction Virtualization (NFV); Use Cases”, October 2013 and ETSI GS NFV002 entitled “Network Function Virtualization (NFV); ArchitecturalFramework”, October 2013, for example.

To provide context to aid in the understanding of network slicing, andthe concept of a network slice, it is helpful to understand that inheterogeneous networks in addition to a plurality of different types ofnodes covering different locations, different infrastructure providersmay own different parts of what is considered as an access network (oreven parts of a core network). For example an M2M virtual networkoperator (VNO) (which may also be referred to as an M2M SP) or anothervirtual service provider may utilize the network resources of a serviceprovider (SP), such as a Telecommunications Service Provider (TCSP). Assuch, the TCSP will create a virtual network (VN) having virtual nodesand virtual links between the nodes. The M2M SP will be able to controlthese virtual network (VN) resources in order to provide service to theVNO's customers. However, the VN (both nodes and links) need to bemapped to physical infrastructure. The VN may only use a subset of thephysical nodes, and each physical node that the VN uses may not be fullyused by that VN. It should also be understood that the M2M SP may makeuse of more than one TCSP, allowing it to create a network formed from aplurality of slices across different networks, effectively having anetwork slice that utilizes resources of a plurality of TCSPs. Ifcertain bandwidth requirements are set for each logical link, thenpercentages of physical links are allocated to create the virtual link.This may also include aggregating links to create a logical link ofgreater capacity than a single physical link. A network slice, from theperspective of an infrastructure provider may only include resources inthe infrastructure provider network. From the perspective of the M2M SP,the network slice is a substantially seamless aggregation of all networkslices that the M2M SP uses which is analogous to the VN. The TCSP dealswith seamlessly connecting the different network slices ofinfrastructure provider resources, along with network slices from theTCSP resources, to create the M2M VN. It should be understood that thesize and nature of different network slices can vary with time as newresources come online or as existing resources are re-allocated. The M2MSP is typically unaware of changes in the underlying physicalinfrastructure.

According to embodiments of the present invention, the communicationnetwork architecture can be based on a Network Function Virtualization(NFV) framework. The NFV Management and Orchestration (MANO) entity isused to instantiate the necessary network functional components in orderto suitably provide the service indentified by a Network Service (NS)request. The instantiation of a network service request is described bya Virtual Network Function Forwarding Graph (VNFFG) which defines theset of network functions that are required to provide the requestedservice. The VNFFG contains a Network Forwarding Path (NFP) that definesa sequence of actions that are to be performed, for example by acollection of VNFs, to provide the requested service.

FIG. 1 illustrates an overview of a communication network architecturein accordance with embodiments of the present invention. The NFV-MANOentity 135 includes an Orchestrator function 140, a Virtual NetworkFunction Manager (VNFM) function 145 and a Virtual InfrastructureManager (VIM) function 150. According to embodiments, the functionalityof the Orchestrator function 140, VNFM function 145 and VIM function 150can be as defined in ETSI GS NFV 001 and ETSI GS NFV 002, for example.

According to embodiments, the VIM function 150 is configured to managethe Network Function Virtual Infrastructure (NFVI) 105 which can includephysical infrastructure, virtual resources and software resources in aNFV based network. For example physical infrastructure can includeservers, storage devices and the like and virtual resources can includevirtual machines. According to embodiments, there can be a plurality ofVIM functions instantiated within a particular NFV architecture, whereineach VIM function is responsible for the management of its respectiveNFVI.

According to embodiments, the VNFM function 145 can be configured tomanage the Virtual Network Functions (VNF) and can manage the lifecycleof the VNFs. For example the VNFM function 145 can create, maintain andterminate VNF instances, which can be installed on virtual machines thatare created and managed by the VIM function 150. The VNFM function 145can also be configured to provide fault, configuration, accounting,performance and security management (FCAPs) of the VNFs. In addition,the VNFM function 145 can be configured to scale-up and scale-down oneor more of the VNFs which can result in the scaling-up and scaling-downof the usage of the central processor(s) that is providing thecomputational power for the realization of the VNFs. In someembodiments, each VNFM function manages a separate VNF or a single VNFMfunction manages multiple VNFs.

According to embodiments the Orchestrator function 140 can be configuredto coordinate, authorize, release and engage the NFVI resources byinteraction with the VIM function 150. The Orchestrator function 140further is configured to create end to end service between differentVNFs by interaction with the VNFM function 145.

With further reference to FIG. 1 , a plurality of network slices and aGlobal Control Plane 110 used for network slice management in accordancewith embodiments of the present invention is illustrated. The GlobalControl Plane 110 controls functions across multiple and potentially allthe network slices. The Global Control Plane 110 may be regarded as aseparate network slice in some embodiments. The illustrated networkslices include a Mobile Broadband (MBB) network slice 120 and a MachineType Communication (MTC) network slice 115. It should be appreciatedthat other types of network slices may be used, for example a slice canbe created for each virtual network. Furthermore a plurality of slicescan be established for each type.

In various embodiments, both the Global Control Plane functions and eachnetwork slice specific control plane functions may be instantiated at anarbitrary location in the network by the NFV-MANO entity in order toprovide connection management across a plurality or all of the networkslices. The location of these functions may depend on performancefactors such as delay requirements of different network services beingprovided.

The functions configured within the Global Control Plane 110 can includethe Global Connection and Mobility Management (G-CMM) function 182,Infrastructure Management (IM) function which can contain a managerfunction and a negotiator function for obtaining computing, storage andnetwork resources for core network functions. In some embodiments the IMfunction contains a Spectrum Manager (IM-SM) function which isconfigured to manage spectrum resources. The Global Control Plane 110can also include a Load Monitor (LM) Function 160, Data Analytics (DA)function 165 and Cache and Forwarding (CF) function 170. Whenimplemented, a Data Analytics (DA) function 165 can be assignedresponsibility for collecting statistics and data across multiple andpotentially all network slices. These statistics and data collected canbe used by the LM 160 in order to manage, evaluate operation conditionsand the like or a combination thereof, for each of the network slices.The Cache and Forward (CF) function 170 is responsible for management ofthe cached content across multiple and potentially all network slices.It should be appreciated the functionality of the DA and LM can becombined in some embodiments, or located elsewhere in the network.

In more detail, the G-CMM function 182 is responsible for maintaining alist of the instantiated network slices and the parameters associatedwith each network slice (e.g. Operator ID, service type, etc.). TheG-CMM function 182 is further responsible for maintaining a pool ofConnection and Mobility Management (CMM) functions, wherein each CMMfunction is instantiated as a local or network slice specific function.The G-CMM function 182 is further responsible for initial association toa network slice. As will be discussed in more detail below, the G-CMMfunction 182 can also be utilized when a slice reselection occurs, inwhich a mobile device, or a group of mobile devices, is migrated fromone slice to another. A slice reselection is also known as a slicehandover (HO).

In embodiments, the network architecture further includes a GlobalCustomer Service Management (G-CSM) function 187 which is configured toreceive the Network Service (NS) Requests 130 and act upon same throughcommunication with the Orchestrator function 140 of the NFV-MANO entity135. For example, a Network Service Request may be indicative of one ormore User Equipment requesting connection to the communication network.The G-CSM function 187 is responsible for maintaining a pool of CustomerService Management (CSM) functions, wherein each CSM function isinstantiated as a local or network slice specific function. The G-CSMfunction 187 is further responsible for keeping track of charging, forexample billing, across multiple or potentially all network slices. TheG-CSM function 187 can be configured to monitor network slices andprovide feedback to the Orchestrator function 140 about the performanceof a network slice. In some embodiments the G-CSM 187 includes a SliceSelection Function SSF 188. The SSF 188 can receive input from the DA165 and/or the LM 160 or alternatively in some embodiments can includethese functions. The G-CSM 187 can thereby enabling optional fine tuningof the network and computing resources for a particular slice, asmanaged by the VNFM function 145 and the VIM function 150. The finetuning can provide for the substantial optimization of the operation ofthe respective network slices in terms of, for example, computingresource usage. As will be discussed in more detail below, the SSF 188can also be utilized when a slice reselection occurs, for example forload balancing. It some embodiments the SSF 188 may instead form part ofanother function, for example the G-CMM function 182, or be instantiatedas a separate network function.

According to embodiments, the G-CSM function 187 can be functionallyintegrated within the Operational Support System/Business Support System(OSS-BSS) 125. The OSS can include functions that support back-officeactivities which aid in operating a communication network, as well asprovisioning and maintaining customer services and the like. The BSS caninclude functions that support customer-facing activities, for examplebilling order management, customer relationship management, call centreautomation and the like. In this embodiment, the G-CSM function 187 cancommunicate with the Orchestrator function 140 using the Os-Ma-nfvointerface, which provides communication between the OSS/BSS 125 and theOrchestrator function 140.

According to some embodiments, the G-CSM function 187 can beinstantiated within the network but external to the OSS/BSS 125. In thisconfiguration, another interface, which may not be defined with the NFVframework, is configured in order to provide communication between theG-CSM function 187 and the Orchestrator function 140.

With further reference to FIG. 1 , the various network slices, forexample the MBB slice 120 and MTC slice 115, may each include their ownnetwork slice specific Connection and Mobility Management (CMM) function181, 180 and Customer Service Management (CSM) function 186, 185. Thenetwork slice specific CMM functions 181, 180 are referred to andcontrolled by the G-CMM function 182 operating within the Global ControlPlane 110. Each network slice further includes a Flow Management (FM)function 176, 175 which can be configured to tune the performance of thenetwork slice by dynamically analyzing, predicting and regulatingbehaviour of data transmitted over that network slice. In addition, eachof the network slices further includes an Authentication andAuthorization (AA) function, which may provide authorization of accessof a UE to use of the communication resources of the particular networkslice.

In some embodiments, each network slice further includes a network slicespecific Infrastructure Management function containing a SpectrumNegotiator function (IM-SN) 191, 190. In some embodiments, the IM-SNfunction is not contained within the network slice but instead mayreside within the Cloud Radio Access Network (C-RAN) functions or aglobal function.

Although only a single Access Point (AP) 100 is shown for clarity, itwill be readily understood that multiple Access Nodes are supported. Insome embodiments, a plurality of access nodes supporting different radioaccess technologies is also supported. In embodiments, an AP throughoutthe various figures may correspond to one or more access nodes,including base stations such as Node B, evolved Node B, a combination ofa Remote Radio Unit (RRU) operatively coupled to one or more BasebandUnit (BBU).

With reference to FIG. 2 , the G-CMM function 182 which can control orinteract with the CMM functions in a plurality network slices can beinstantiated close to the AP 100. In this embodiment, the LM function160 can also be instantiated close to the AP 100 along with the G-CMMfunction 182. In some embodiments, the processing functions of an AP maybe physically separated from the radio head, and instantiated within adata center. In such embodiments, it is possible that a single G-CMMfunction 182 can be instantiated within a data center that also providesthe processing functions for a plurality of APs.

With reference to FIG. 3 , a Slice Management control plane function 155which includes the G-CMM function 182 and the LM function 160, isinstantiated within the network architecture. The Slice Managementcontrol plane function 155 can be located within the RAN or close to theCore network/RAN boundary. In some embodiments the Slice Managementcontrol plane function 155 can include other functions, such as theG-CSM function 187 and/or the DA function 165.

In accordance with embodiments of the present invention, the NFV-MANOentity 135 further instantiates NFV management plane functions thatdefine the network topology for a Network Service (NS) request;determine the transport protocols to be used across links; and determinethe underlying links between different network functions used by thenetwork service. In some embodiments, these NFV management planefunctions are integrated within the Orchestrator function 140 andinclude a Software Defined Topology (SDT) function 197, a SoftwareDefined Protocol (SDP) function 196 and a Software Defined ResourceAllocation (SDRA) function 192 and an Infrastructure Manager (IM)function 194.

Software Defined Networking (SDN) is a network management technique thatallows a network management entity (e.g. an SDN Controller) to implementan architectural framework to create intelligent programmable networks,where the control planes and the data planes can be decoupled, networkintelligence and state are logically centralized, and the underlyingnetwork infrastructure is abstracted from the application. Inembodiments of the present invention, the Orchestrator function mayinstruct the instantiation of virtual network functions connected toform a network logical topology, for example as defined by the SoftwareDefined Topology (SDT) function. The SDT function can be combined withthe SDN and Software Defined Protocol (SDP) function to create acustomized virtual network, wherein a virtual network is a collection ofresources virtualized for a particular service.

According to embodiments, the SDT function 197 is instantiated as partof the Orchestrator function 140. The SDT function 197 is configured todetermine the Point of Presence (PoP) for each VNF in the VNF ForwardingGraph (VNFFG) provided by the G-CSM function 187. The SDT function 197is also configured to determine the logical links between the VNFs inthe VNFFG.

According to embodiments, the SDRA function is configured to allocatethe underlying link resources for each logical link defined in theVNFFG. The SDRA function may utilize other functional components, suchas the SDN Controller (SDN-C) function 193 and the Traffic Engineering(TE) function 195. The SDN-C function 193 is instantiated within eachVIM function 193 and is configured to provide the forwarding rules tothe forwarding switches, for example routers and the like within thephysical network architecture. The TE function 195 is instantiatedwithin the Orchestrator function 140 and is configured to perform pathcomputation between the source node and destination node whileattempting to tune the path by dynamically analyzing, predicting andregulating behaviour of data transmission. According to embodiments, theSDP function 196 is instantiated as part of the Orchestrator function140. The SDP function 196 is configured to determine the transportprotocol stack for each of the logical links defined in the VNFFG.

FIG. 4 illustrates a system for virtual infrastructure managementincluding first and second Operators having internal InfrastructureManagement functions in accordance with embodiments of the presentinvention. The system comprises an Operational Support System/BusinessSupport System (OSS/BSS) function 125, one or more Slice SpecificVirtual Network Functions (SSVNFs) 45, Network Function VirtualizationInfrastructure (NFVI) 105, a first NFV-MANO entity 135, and a secondNFV-MANO entity 235.

As shown in FIG. 4 , the first NFV-MANO entity corresponds to a firstoperator (Operator A) and comprises a first Orchestrator function 140,one or more Virtual Network Function Managers (VNFM(s)) 145, and one ormore Virtual Infrastructure Managers (VIM(s)) 150. The Orchestratorfunction further comprises a Broker (e.g. Spectrum Broker), a Negotiator(e.g. Spectrum Negotiator) 194, a Software Defined Topology (SDT)function 197, a Software Defined Protocol (SDP) function 196, and aTraffic Engineering (TE) function 195. The VIMs further comprise aSoftware Defined Network Controller (SDN-C) function 193. TheOrchestrator function is communicatively coupled to the G-CSM of theOSS/BSS, while the VNFM(s) are communicatively coupled to the ElementManager (EM) 46 and VNF 47 of the SSVNF(s) 45, while the VIM(s) arecommunicatively coupled to the NFVI 105. The functionality of theOrchestrator, VNFM, and VIM functions may be defined in ETSI GS NFV 001and ETSI GS NFV 002, for example.

Still referring to FIG. 4 , the second NFV-MANO entity 235 correspondsto a second operator (Operator B) and comprises the same set offunctional elements as the first NFV-MANO entity 135. These functionalelements in the second operator network include a Orchestrator function240, one or more Virtual Network Function Managers (VNFM(s)) 245, andone or more Virtual Infrastructure Managers (VIM(s)) 250. The secondOrchestrator function further comprises a Broker, a Negotiator 294, aSoftware Defined Topology (SDT) function 297, a Software DefinedProtocol (SDP) function 296, and a Traffic Engineering (TE) function295. The VIM(s) further comprise a Software Defined Network Controller(SDN-C) function 293. The first and second NFV-MANOs are communicativelyinter-coupled through their respective Orchestrators, via theOrchestrator-Orchestrator interface (Or-Or) 234.

The system of FIG. 4 may be used for managing network resources, forexample, when the first NFV-MANO entity (Operator A) cannot satisfy arequest for additional computing, storage, and network resources. Forexample, when a link is congested and no new paths can be configured toresolve the congestion, or if there are not enough resources for anetwork function to perform a scale-up or scale-out operation.Accordingly, the first NFV-MANO entity 135 may communicate with thesecond NFV-MANO entity 235 in order to obtain additional resources. Sucha request is passed through the Or-Or interface 234.

In operation, the Global Customer Service Management (G-CSM) function187 of the OSS/BSS receives a request, such as a Network Service Request(NS Request). The G-CSM then determines whether the NS Request can beaccommodated on an existing network slice using the current (SSVNFs)with or without modification, or whether a new network slice isrequired. This determination is then sent to the first Orchestratorfunction, which proceeds to instantiate each necessary function forprovision of the NS Request by creating a new network slice (i.e.instantiating a new set of SSVNFs) or adding any necessary functions toan existing network slice (SSVNF).

Each SSVNF 45 comprises an Element Manager (EM) 46 and a Virtual NetworkFunction (VNF) 47, which functions to evaluate the services in the NSRequest and determine whether there are sufficient resources to carryout the services. If there are insufficient resources, the SSVNF maysend a trigger to the first NFV-MANO entity to request additionalresources. In certain embodiments, the NFVI may also determine whetherthere are sufficient resources, and may also send a trigger to the firstNFV-MANO entity if more resources are needed.

The first Orchestrator function of the first NFV-MANO entity can receivethe trigger through a variety of possible routes including: i) from theVNF or EM of the SSVNF 45 via the OSS/BSS 125; ii) from the VNF 47 ofthe SSVNF 45 via the VNFMs 145 of the first NFV-MANO entity; and iii)from the NFVI 105 via the VIMs 150 of the first NFV-MANO entity 135.Triggers initiated by the VNF of SSVNF may be based on performancemetrics measure by the VNF. If the first Orchestrator functiondetermines that there are insufficient resources to grant the request,it may send a request to the second Orchestrator function of the secondNFV-MANO entity. The request may be sent from the Negotiator 194 of thefirst Orchestrator function 140, to the Broker of the secondOrchestrator function 240 via the Or-Or interface 234.

While FIG. 4 depicts the first NFV-MANO entity corresponding to a firstoperator (Operator A), and the second NFV-MANO entity corresponding to asecond operator (Operator B), in other embodiments, each NFV-MANO entitymay correspond to the same operator. For example, the second NFV-MANOentity may be instantiated by Operator A in order to provide or managespectrum resource requests.

Slice handover (HO), also referred to as slice switching or slicereselection, is now discussed. Slice handover/reselection refers to aprocess where a UE is served by a first slice, but due to mobility orother reasons, the UE is moved to another slice to receive networkservices. There are several reasons why moving a UE from a first sliceto a second slice (a slice handover, or a slice reselection) may occur.One reason may be due to UE mobility. In this case, a user is attachedto a first slice, and moves to a location that is not served byresources in the slice. To continue supporting the UE, the network canhave the UE handed over to a second slice. In some cases, switching fromone network slice to another may result in a change of performance (e.g.degraded performance). Another reason for a slice handover can be due toservice requirement changes: For example, it may be desirable to switchfrom a network slice with high mobility support (e.g. when the UE istravelling at high speed on a highway) to low mobility support (e.g.when the UE moves into an urban area).

In addition to mobility related slice reselection, Slice reselection mayalso be triggered by a determination that the resources allocated to anetwork slice are overloaded. In this case, slice reselection can beused for load balancing by moving UE traffic from the overloaded sliceto another slice. Such a slice reselection may be temporary, until a newslice is created or existing slices are reconfigured. Slice reselectionmay also be triggered by the completion of a slice management event.Slice management events include the addition (instantiation), deletion,and modification of a slice. Examples of these slice management eventswill now be provided. An NO may provide access to devices through MBBslice 120, and as MTC devices are added, they may be served through theMBB slice. When an MTC specific slice is created, a slice reselectionprocedure for the MTC devices may be undertaken to handover the devicesto the new MTC slice in this example of a slice addition. If there is anMTC slice but there are an insufficient number of connected devices tojustify the overhead associated with the slice, the slice can bedeleted, but before this happens, the devices served by the soon-to-bedeleted slice can undertake a slice reselection procedure so that theycan be served by a different slice. If a slice is modified by adding tothe allocated resources, the slice may be able to support more devices(and may also be able to support devices with heavier demands on theresources), and accordingly, devices in other slices may be selected toundertake a slice reselection process. If the slice modificationincludes decreasing the resources allocated to a slice, the mobiledevices served by the slice, may undertake a slice reselection processto move some of the devices to other slices. It should be noted thatthere may be a process by which the devices that undergo a slicereselection process are selected and instructed. In situations in whicha service that a slice can support will change, devices that require theservice in question may be selected and instructed to request slicereselection.

Typically if the UE undergoes a handover to an access point that doesnot support the currently associated slice, a slice handover/reselectionprocedure is initiated. However, in some circumstances, for example forwhen a new slice is added to support a particular service, the new slicemay include the same AP, if the AP is capable of belonging to twodifferent slices.

An intra-operator handover, or an intra-operator reselection, is a termused to refer to a slice reselection procedure in which both the initialslice and the target slice are operated by the same service provider.FIG. 5 illustrates a procedure for such an intra-operator handover,according to an embodiment. In FIG. 5 , a measurement report 301 is sentfrom the UE to the serving AP, also called the source AP 100. Thismeasurement report indicates the need for a handover. For example, themeasurement report 301 may indicate the UE is receiving a strongersignal from another AP (called the target AP 101) than from the sourceAP 100. Such a measurement report triggers the handover/reselectionprocess if the target AP 101 supports a different set of slices than thesource AP 100. It should be appreciated that other triggers arepossible. For example, the source AP 100 may trigger the handover if itsreception from the UE drops below a threshold. Alternatively, in someembodiments the CMM 183, which keeps track of the UE's location, maytrigger the handover, for example in the case of location prediction. Itwill be understood that in embodiments in which a slice handover istriggered by a node other than the AP 100, it is possible for thehandover procedure to start without involving the AP 100. As notedabove, the CMM 183 is another node that could initiate a handoverprocess, and in such as a case, the CMM 183 can transmit a message thatwould take the place of the measurement report.

Returning to FIG. 5 , the source AP sends an HO command 302, which canalso be called a reselection request or command, to the target AP 101,which belongs to a different slice. An AP 100 serving a UE, andconnecting the UE to the first slice, can determine, based oninformation associated with the UE, including an estimated trajectoryand information from the UE pertaining to which other APs can be seen.Based on the knowledge of network topology and slice support, AP 100 candetermine both which AP the UE is likely to be next served by, andwhether the UE should be moved to a different slice. The handovercommand is forwarded 303 from the target AP 101 to the G-CMM 181. Inthis example, the HO command 303 can be considered a trigger to initiatea slice reselection. Those skilled in the art will appreciate that theHO command 303 need not include an explicit selection of the slice thatthe UE will be moved to, and instead can, in some embodiments, containenough information so that another entity such as the CMM can make thehandover decision. The slice reselection event in this example is eitherthe generation or receipt of the measurement report 301 that includesidentification of a high likelihood of a need for a slice handover. TheG-CMM 182, in this example includes a slice selection function (notshown), which performs the slice association and CMM selection process310. When a new slice (NS) has been determined, the NS ID, andoptionally the ID of CMM 183 is sent 315 to the target AP 101. If the IDof the CMM is not selected by the slice selection function then it canbe selected by the target AP 101. In the meantime, a call admissionprocess may be initiated by the target AP 101 to admit the device. Thiscan include the target AP 101 sending an HO command includingauthentication credentials 318 to the CMM 183 of the new slice, andreceiving an acknowledgement (ACK) 320 from the CMM 183. The target AP101 then sends an ACK 321 to the source AP 100. Once the sliceassociation and CMM selection process 310 is completed, the source AP100 instructs the UE to reconfigure the Radio Resource Control (RRC)Connection 325. The RRC reconfiguration message 325 includesinstructions that cause the UE to establish a radio connection 320 tothe Target AP 101 (which is analogous to a radio bearer in LTE) tocomplete the handover. In an alternate embodiment, Source AP 100 andtarget AP 101 do not need to directly communicate with each other, andinstead HO command 302 is transmitted from the source AP 100 to theG-CMM 182 or the CMM 183. The G-CMM 182 can select the appropriate sliceand perform the slice selection as indicated in 310. Instead of targetAP 101 transmitting ACK 321 to AP 100, the ACK can be sent to the G-CMM182, which would then send an ACK to the source AP 100. In thisembodiment, there is still an HO command 302 transmitted towards AP 101,but it is routed through network infrastructure instead of goingAP-to-AP.

It should be noted that in situations in which an appropriate slice isnot available, the G-CMM may use a default slice selection. In someembodiments, the default slice (also referred to as a common slice) willbe a mobile broadband slice 120. Further, in other embodiments, theslice selection function may not be instantiated within the G-CMM 182,but instead can instantiated within the G-CSM 187, or some otherfunction, for example a global slice manager (not shown), or beimplemented by a host as a separate function.

If intra-operator handover is either not possible or otherwise notpreferred, then an inter-operator (Inter-op) handover can be performed.An Inter-op handover occurs when a mobile device associated with a slicein a first network operated by a first Operator (Operator A) is migratedto a slice in a second network operated by a second Operator (OperatorB). For inter-operator handover, two example options are discussed. FIG.6 illustrates an embodiment of a process according to a first option, inwhich the inter-operator handover request is sent from the source G-CSMto the target G-CSM. This request may use an Or-Or interface 234(discussed above with reference to FIG. 4 ). Referring to FIG. 6 , nodesin the first network are shown in solid line, and nodes in the secondnetwork are shown in dotted line. The UE sends a measurement report 360to the source AP 100, in a similar manner as described above. Similaralternative triggers for the handover as discussed above also apply. Aninter-op HO request 363 is sent to the source G-CMM 351, which forwardsthe request 365 to the source G-CSM 352. In one example, the source AP100 sends an inter-op HO request 363 to the Source G-CMM 351 because itcan determine that no Target AP that the UE can access is within thesame network. In one embodiment, the inter-op HO request 363 specifiesthat it is a request to handover the UE service to a slice withinanother network, while in other embodiments, the inter-op HO request 363is simply a handover request message that serves as a trigger for aninter-op handover. The source G-CSM 352 the forwards the inter-op HOrequest 367 to the target G-CSM 353 using the Or-Or interface 234. Thetarget G-CSM 353 selects a target G-CMM 354 and forwards the request 368to the target G-CMM 354. In this example target G-CMM 354 includes theslice selection function (not shown) which performs the sliceassociation and local CMM selection process 370. A slice migrationprocess occurs by sending target slice and CMM information to the UE viathe source AP 100 using inter-op HO responses 371-375 as shown, andestablishing a connection 378 between the UE and the target AP 101.Those skilled in the art will appreciate that AP 100 can generate the HOrequest 363 in accordance with the receipt of measurement report 360from the UE. The measurement reports may include signal strengthreadings from APs that the UE can see. If AP 100 determines, for examplein accordance with a projection of the UE trajectory, that the UE willbe moving out of the AP's service area, and will not be served by otherAPs in the same network, the inter-op HO request 363 can includeinformation identifying the APs that the UE may connect to. This allowsthe source G-CMM 351 to select the Target AP 101 that the UE shouldconnect to.

FIG. 7 illustrates an inter-operator slice reselection process accordingto a second option, in which the inter-operator handover request is sentthrough the source G-CMM to the target G-CMM. This option reduces thesignaling overhead compared to the example process illustrated in FIG. 6, but it requires an interface between G-CMMs. Those skilled in the artwill appreciate that unlike the method of FIG. 7 , the methodillustrated in FIG. 6 can re-use an existing Or-Or interface 234. Asexplained above with reference to FIG. 4 , the network would typicallyalready have an Or-Or interface 234 in place to allow networks tocommunicate with each other to enable the sharing resources for newservice requests. The process illustrated in FIG. 6 can use thisinterface for passing messages used during a slice reselection process.The example process illustrated in FIG. 7 can reduce the amount ofrequired signaling from process shown in FIG. 6 , assuming a interfaceis established between a source G-CMM 351 in operator A's network and atarget G-CMM 354 in operator B's network. In FIG. 7 target G-CMM 354includes a slice selection function (not shown) which can perform theslice association and CMM selection process 430. If G-CMM 354 does nothave a slice selection function, it can send a message to an externallyinstantiated slice selection function within its network (much as anyfunctional entity described above or below could function without aninternally instantiated slice selection function). Referring to FIG. 7 ,in which nodes in the first network are shown in solid line, and nodesin the second network are shown in dotted line, the UE sends ameasurement report 410 to the source AP 100, in a similar manner asdescribed above. Similar alternative triggers for the handover asdiscussed above also apply. An inter-op HO request 420 is sent to thesource G-CMM 351, which forwards the request 425 to the target G-CMM 353using the Or-Or interface 234. The target G-CMM 354 selects a targetG-CMM 401. In this example target G-CMM 354 includes a slice selectionfunction (not shown) which performs the slice association and CMMselection process 430. A slice migration process occurs by sendingtarget slice and CMM information to the UE via the source AP usinginter-op HO responses 440, 445 and 450 as shown, and establishing aconnection 455 between the UE and the target AP 101.

FIG. 8 illustrates a procedure for slice reselection for load balancingaccording to embodiments of the present invention. As noted in earlierfigures, the Slice Selection function can be instantiated in the CSM, aswell as in the CMM. For the sake of completeness, FIG. 8 provides anillustration of a method in which the CSM hosts the slice selectionfunction. It will be understood that this could be applied to theearlier disclosed methods, much as the use of the CMM instead of the CSMas the entity hosting the slice selection function, could be applied tothe method of FIG. 8 . FIG. 8 illustrates an example of a slicereselection event occurs when differing capacities between networkslices reaches a load-balancing threshold. FIG. 8 illustrates an examplewhere a monitoring function (e.g. for example LM 160) monitors the slicenetwork resource utilization. In some embodiments, such a threshold maybe triggered when the utilization of the source slice reaches athreshold. In other embodiments the threshold may depend on a comparisonbetween slices, for example the difference in utilization between asource slice and a target slice. A load monitoring function, for exampleLM 160, sends the monitored capacity information 501 (i.e., themonitored slice utilization) to the G-CMM function 182. The G-CMMfunction can evaluate the received capacity information. The receipt ofthe capacity information can serve as a slice reselection event whenreselection is performed in accordance with a need to load balancebetween slices. The G-CMM function 182 then transmits a HO request 502(in some embodiments, this message can serve as a trigger for the slicereselection process) to a slice selection function, which in thisexample is part for G-CSM 187. In other embodiments the threshold can bedetected and transmitted by another function which monitors sliceresource utilization, for example DA function 165 of FIG. 1 . The sliceselection function (not shown) then performs a slice association and CMMselection process 503 to determine to which slice the UE(s) should bemigrated. It is noted that for a slice reselection based on capacity orload-balancing, a group of UEs may be migrated at once. In theillustrated embodiment, G-CSM 187 sends an HO request 505 to the targetCMM 183 of the new slice, and receives an acknowledgement (ACK) 507 fromthe CMM 183. If this is an intra-operator slice reselection, the G-CSM187 will likely not need to confirm the availability of resources, butin an inter-operator slice reselection, this request and ACK exchangemay be used to ensure that the target slice can support the UEs beingmigrated. The G-CSM 187 also sends an HO response 440 back to the G-CMM182. The G-CSM 187 initiates the migration of the UE (or a group of UEs)to the new slice by sending an HO instruction 445 including the slice IDfor the new slice to the Source AP 100, which forwards the informationin HO instruction 450 to the UE. This allows for the establishment ofradio connection 455 to be established with target AP 101 of the newslice to perfect the migration.

FIG. 9 . is a flowchart illustrating a procedure for slice reselectionaccording to embodiments of the present invention. FIG. 9 illustratesmethod steps that can be executed by a host processing system toimplement a slice selection function. The steps shown in dashed line areoptional. Steps indicated as optional may not be needed in someembodiments. Boxes with rounded corners indicate functions that may bedistinct from the slice selection function and can provide input to theslice selection function.

At step 910 the slice selection function receives an indication that aslice reselection triggering events has occurred. This indication istypically received from another node or function in the network,including the load manager, the C-CMM, and the Source AP. In some casesthe slice selection function receives data which it evaluates todetermine that slice reselection triggering events has occurred. Onesuch example is that the Source AP may send information based on accessnetwork conditions that it can observe, in addition to UE observednetwork conditions, so that the slice selection function can determinewhether slice reselection is an appropriate action. In other cases, theslice selection function can receive a trigger message, when anothernode or function has determined that a slice reselection is required(typically as a result of an observed event). It should be understoodthat if a function such as a Load Monitor determines that a slicereselection is required, from the perspective of the Slice SelectionFunction, the transmission of a slice reselection instruction is anexternal event that can trigger the slice reselection process. As notedpreviously, there are several possible slice reselection triggeringevents. These events can be detected at different nodes and functions.When the node or function detecting the slice selection function is notthe slice selection function itself, the slice selection function mayreceive the indication in the form of a message. In some embodiments theslice reselection triggering event is selected from the group consistingof:

the mobile device moves such that the mobile device has a clearerchannel to an Access Point in another slice (e.g. roaming);

a slice management event, such as creating a slice, deleting a slice ormodifying the parameters of a slice, occurs; and

a load balancing threshold is met.

Accordingly, the trigger can be received by the slice selection functionfrom the source AP, from the G-CMM, from the Load Monitor, or from someother function.

For example, if the UE is an MTC device, but it is the first MTC deviceadmitted to the network, then a separate MTC slice 115 may not have beeninstantiated. Without an MTC slice, the MTC device may be assigned to adefault slice, such as the MBB slice 120. As more MTC devices attach tothe network, MTC slice 115 can be created. Creation of a slice, in thiscase MTC Slice 115, is a slice management event. In this example, whenMTC slice 115 is created there may be benefits to moving any MTC deviceon the MBB slice 120 to the MTC slice 115. As such, the creation of MTCSlice 115 is a slice reselection triggering event. This slicereselection triggering event is associated with any MTC devices admittedto the MBB slice 120. In another example, after the instantiation of MTCSlice 115, if a sufficient number of MTC devices attached to the MTCslice 115 are deactivated, there may no longer be sufficient traffic tojustify allocating network resources to the MTC slice 115. Accordinglythe MTC slice may be scheduled for termination. The determination thatthe MTC Slice 115 is going to be deleted is a slice management event. Inthis example, determining that the slice is to be deleted is the slicereselection triggering event. When it is determined that the MTC slice115 is to be deleted, any MTC devices attached to the MTC slice 115 aremoved to the default MBB slice 120. As another example, the resourcesallocated to a particular slice may change, with some slices beingallocated more or less resources. Such a slice management event can alsotrigger a slice reselection.

In some embodiments, the slice selection function, upon receiving anindication of a slice reselection trigger event in 910, can determine930 if the slice reselection is to be an inter-operator orintra-operator slice handover. As noted above, this determination can bemade in accordance with data from the source AP, the UE measurements,and other information including agreements with other network operators.In accordance with the data from the AP and the UE, the slice selectionfunction can determine which APs are likely to provide the best serviceto the UE. If the serving AP is at or near the edge of the networkcoverage, an interoperator handover will be likely. In which case theslice handover can be accomplished using an intra-operator HO, forexample as discussed with reference to FIG. 5 . If so, theintra-operator procedure is implemented. Alternatively, the new networkslice belongs to a different operator network than the slice previouslysupporting the mobile device. In which case an inter-operator procedureis implemented, for example as discussed with reference to theembodiments illustrated in FIGS. 6 and 7 . In some embodiments thesource AP, knowing that it is not at the edge of the coverage area ofthe network can default to trying an intra-OP request unless instructedotherwise. As noted above, the source AP can send a handover requesttowards a potential target AP in the same network (i.e., a firstnetwork), either directly or through a function such as the CMM. If thesource AP is at the edge of coverage, it can determine based on the UEmeasurement reports that the UE is leaving the network coverage area.This will likely result in an Inter-operator handover. The Source AP cansend the handover request towards the slice selection function. In theembodiments illustrated in FIGS. 5-7 , the slice selection function(SSF) is instantiated as a part of within the G-CMM function. Aspreviously stated, the SSF may instead be instantiated as a part of theG-CSM function, as illustrated in FIG. 1 and FIG. 8 . In otherembodiments, it can be instantiated as part of another function orinstantiated as a separate function.

At step 940, the slice selection function selects a new slice as atarget slice. This can be implemented by making a slice associationdecision and then selecting a CMM function for the target slice. It willbe well understood that when a device such as a UE attaches to a networkit is assigned a slice, typically based on its service requirements. Anynumber of different processes can be used to carry out this so-calledslice association process. These processes that are suitable for initialslice association can be used (sometimes with minor modifications thatwould be apparent to those skilled in the art) as slice-reselectionprocesses. It will be understood that in some embodiments a restrictionwould be placed on a slice selection function to not select the slicethat the UE is already associated with.

Finally at step 950 the slice selection function initiates the migrationof the mobile device to the target slice. In some embodiments thisincludes sending messages to network components (which can includenetwork functions and APs) in order to migrate the mobile device to thetarget slice.

In some embodiments, a group of devices, or in some cases all of thedevices associated with a slice, may be migrated to a differentoperator, which can be triggered for reasons other than mobility. Forexample, a particular enterprise may have VNs established with twowireless network operators (WNOs). In some embodiments, the enterprise,via the source G-CMM, can request the VN be moved from a slice operatedby a first WNO to a second slice operated by the second WNO. Althoughthis may be viewed as a handover of a slice, it is possible that thiswould be implemented by creating a slice on the new operator, andperforming a migration of the user data along with a forced handover ofthe UEs.

It will be readily understood that, throughout the preceding discussion,the above-described network functionalities and operations maycorrespond to a method for use in supporting operation a communicationnetwork, such as a 5G wireless communication network. The method mayinvolve computer-implemented functions, namely functions which areimplemented by one or more computing, communication and/or memorycomponents of the network infrastructure. These components may takevarious forms, such as specific servers or general-purpose computing,communication and/or memory devices which are configured to provide therequired functionality through virtualization technologies. The methodmay involve the operation of one or more network components in order toimprove the operation of the network. As such, with the communicationnetwork viewed as an apparatus, embodiments of the present invention maybe directed to improving internal operations of the communicationnetwork.

Further, it will be readily understood that embodiments of the presentinvention relate to a communication network system or associatedapparatus thereof, which is configured to perform the above-describednetwork functionalities and operations. Again, the system or apparatusmay comprise one or more computing, communication and/or memorycomponents of the network infrastructure, which may take various forms,such as specific servers or general-purpose computing, communicationand/or memory devices which are configured to provide the requiredfunctionality through virtualization technologies. Various methods asdisclosed herein may be implemented on one or more real or virtualcomputing devices, such as devices within a communication networkcontrol plane, devices operating in the data plane, or a combinationthereof. Computing devices used to implement method operations mayinclude a processor operatively coupled to memory, the memory providinginstructions for execution by the processor to perform the method asdescribed herein.

Various embodiments of the present invention utilize real and/or virtualcomputer resources. Such computer resources utilize, at a hardwarelevel, a set of one or more microprocessors operatively coupled to acorresponding set of memory components which include stored programinstructions for execution by the microprocessors. Computing resourcesmay be used to provide virtual computing resources at one or more levelsof virtualization. For example, one or more given generic computerhardware platforms may be used to provide one or more virtual computingmachines. Computer hardware, such as processor resources, memory, andthe like, may also be virtualized in order to provide resources fromwhich further virtual computing machines are built. A set of computingresources which are allocatable for providing various computingresources which in turn are used to realize various computing componentsof a system, may be regarded as providing a distributed computingsystem, the internal architecture of which may be configured in variousways.

FIG. 10 is a block diagram of a processing system 1001 that may be usedfor implementing the various network elements which instantiate thefunctions defined herein, for example a host implementing a SliceSelection function, a Slice manager function, or a CMM function, a CSMfunction, or the like. As shown in FIG. 10 , processing system 1010includes a processor 1010, working memory 1020, non-transitory storage1030, network interface 1050, I/O interface 1040, and depending on thenode type, a transceiver 1060, all of which are communicatively coupledvia bi-directional bus 1070.

According to certain embodiments, all of the depicted elements may beutilized, or only a subset of the elements. Further, the processingsystem 1001 may contain multiple instances of certain elements, such asmultiple processors, memories, or transceivers. Also, elements ofprocessing system 1001 may be directly coupled to other componentswithout the bi-directional bus.

The memory may include any type of non-transitory memory such as staticrandom access memory (SRAM), dynamic random access memory (DRAM),synchronous DRAM (SDRAM), read-only memory (ROM), any combination ofsuch, or the like. The mass storage element may include any type ofnon-transitory storage device, such as a solid state drive, hard diskdrive, a magnetic disk drive, an optical disk drive, USB drive, or anycomputer program product configured to store data and machine executableprogram code. According to certain embodiments, the memory or massstorage have recorded thereon statements an instructions executable bythe processor for performing the aforementioned functions and steps ofplural components defined above.

Through the descriptions of the preceding embodiments, the presentdisclosure may be implemented by using hardware only or by usingsoftware and a necessary universal hardware platform. Based on suchunderstandings, the technical solution of the present disclosure may beembodied in the form of a software product. The software product may bestored in a non-volatile or non-transitory storage medium, which caninclude a compact disk read-only memory (CD-ROM), flash memory, or aremovable hard disk. The software product includes a number ofinstructions that enable a computer device (computer, server, or networkdevice) to execute the methods provided in the embodiments of thepresent disclosure. For example, such an execution may correspond to asimulation of the logical operations as described herein. The softwareproduct may additionally or alternatively include number of instructionsthat enable a computer device to execute operations for configuring orprogramming a digital logic apparatus in accordance with embodiments ofthe present disclosure.

Although the present invention has been described with reference tospecific features and embodiments thereof, it is evident that variousmodifications and combinations can be made thereto without departingfrom the invention. The specification and drawings are, accordingly, tobe regarded simply as an illustration of the invention as defined by theappended claims, and are contemplated to cover any and allmodifications, variations, combinations or equivalents that fall withinthe scope of the present invention.

I claim:
 1. A communication system comprising a slice selection function(SSF) and a connection and mobility management (CMM) function, whereinthe SSF is configured to: when a slice reselection triggering eventassociated with a mobile device attached to a first slice has occurred,select a second slice to serve the mobile device and send informationabout the second slice to the CMM function; the CMM function isconfigured to: obtain the information about the second slice from theSSF, and instruct the mobile device to connect to the second slice. 2.The system of claim 1 wherein the slice reselection triggering eventcomprises a slice management event.
 3. The system of claim 2 wherein theslice management event is indicative that the first slice isunavailable.
 4. The system of claim 1 wherein the slice reselectiontriggering event comprises a movement of the mobile device.
 5. Thesystem of claim 1 wherein the slice reselection triggering eventcomprises a change in the service requirements of the mobile device. 6.The system of claim 1 wherein the SSF is further configured to send theinformation about the second slice in response to a query from the CMMfunction.
 7. The system of claim 1, wherein the CMM function isconfigured to instruct the mobile device to connect to the second sliceby sending information about the second slice to the mobile device. 8.The system of claim 1, wherein the CMM function is further configured tosend information associated with a target CMM to an access pointassociated with the first slice.
 9. A non-transitory computer-readablemedium storing instructions which, when executed by a processor, causethe processor to: when a slice reselection triggering event associatedwith a mobile device attached to a first slice has occurred, select asecond slice to serve the mobile device; and send information about thesecond slice to a connection and mobility management (CMM) function. 10.The non-transitory computer-readable medium of claim 9 wherein the slicereselection triggering event comprises at least one of: a slicemanagement event, a movement of the mobile device, or a change in theservice requirements of the mobile device.
 11. The non-transitorycomputer-readable medium of claim 10 wherein the slice management eventis indicative that the first slice is unavailable.
 12. Thenon-transitory computer-readable medium of claim 10 wherein theinstructions which, when executed by the processor, further cause theprocessor to: send the information about the second slice in response toa query from the CMM function.
 13. A method for network slicereselection comprising: when a slice reselection triggering eventassociated with a mobile device attached to a first slice has occurred,obtaining, by a connection and mobility management (CMM) function,information about a second slice from a slice selection function (SSF),wherein the second slice is used to serve the mobile device; andinstructing, by the CMM function, the mobile device to connect to thesecond slice.
 14. The method of claim 13 wherein the slice reselectiontriggering event comprises at least one of: a slice management event, amovement of the mobile device, or a change in the service requirementsof the mobile device.
 15. The method of claim 14 wherein the slicemanagement event is indicative that the first slice is unavailable. 16.The method of claim 13 wherein the second slice is selected by the SSF.17. The method of claim 13, wherein instructing the mobile device toconnect to the second slice comprises sending, by the CMM function,information about the second slice to the mobile device.
 18. The methodof claim 13, wherein the method further comprises: sending, by the CMMfunction, information associated with a target CMM to an access pointassociated with the first slice.
 19. An apparatus comprising: aprocessor; and a non-transient memory for storing instructions whichwhen executed by the processor cause the apparatus to: when a slicereselection triggering event associated with a mobile device attached toa first slice has occurred, obtain information about a second slice froma slice selection function (SSF), wherein the second slice is used toserve the mobile device; and instruct the mobile device to connect tothe second slice.
 20. A non-transitory computer-readable medium storinginstructions which, when executed by a processor, cause the processorto: when a slice reselection triggering event associated with a mobiledevice attached to a first slice has occurred, obtain information abouta second slice from a slice selection function (SSF), wherein the secondslice is used to serve the mobile device; and instruct the mobile deviceto connect to the second slice.